The Salesforce Lightning interface has been with us for a while now and with each new release, it keeps getting better and better. Salesforce continues to add functionality and features, so for those of you that have not looked at the Lightning Experience lately, you may be surprised at what is available.
Below are some links from the Salesforce help files to point you in the right direction, if you are interested in exploring what is new, how to switch, and what is still different or not available in the Lightning Experience. These are dynamic and updated for each release so if you are still deciding, be sure to check periodically for the feature you want.
Saying Hello to Lightning Experience Doesn’t Mean Saying Goodbye to Salesforce Classic:
https://help.salesforce.com/articleView?id=lex_switching_uis.htm&type=0
What are the Gaps between Lightning Experience and Salesforce Classic:
Gotchas If Users Switch Between Lightning Experience and Salesforce Classic:
https://help.salesforce.com/articleView?id=lex_switching_considerations.htm&type=0